Forced-draft fan



1929. F. E. .GRUNWALDT v 1,736,311

FORCED DRAFT FAN Filed Jun 14. 1927 2 Sheets-Sheet 1 F7006 gill/7W0? I Nov. 19', 1929.

F. E. GRUNWALDT 1,736,311

FORGED DRAFT FAN 2 Sheets-Shea? 2 Filed June 14. 1927 Qwomtoz Fran/r tfrunwa/dr Patented 1e, A 3,?"36311 warren STA as PTENT orricr.

FRANK E. GRUNVJALDT, F SEATTLE, WASHINGTON FORCED-DRAFT FAN Application filed June 14, 192?. Serial No. 188,734.

The invention is a fan adaptable-to be in- Figure is a detail showing a connection stalled in connection with the inlet air duct between the end of a duct and a furnace housof hot air heating furnaces which operates ing to show that the duct is insulated against in the duct and does not decrease the area of I vibration and noise by a deadening washer the duct to any appreciable amount. at all connections. 5 The object of the invention is to provide a Figure 6 is a view showing an alternate fan for a forced draft in a furnace inlet duct arrangement in which the fan is located in the which operates in the duct and at the same side ofastraight duct. time does not decrease the area to any ap- In the drawings the device is shown as it preciable amount. would be made wherein numeral 1 indicates Another object of the invention is to prothe fan, numeral 2 the fan housing, and nuvide a fan for a forced draft duct which opmeral 3 the duct. crates in one side of the duct and at the same The fan is constructed as shown in Figures time increases the velocity of the air in the 3 and 4 with a cylinder 5 having closed ends entire duct. formed with solid hubs 6 and 7 flanged at 65 Another object of the invention is to pro their outer edges and at their centers and vide means for forcing air through a duct mounted on a shaft 8 and it will be seen that in which a battle is used in combination with the interior of the cylinder is sealed. The a fan to increase or decrease the area adjacent shaft 8 is mounted in bearings 9 and 10 which the fan to vary the pressure or velocity. are supported in posts 11 and 12. In the de- 7 A further object of th invention is to prosign shown the posts are illustrated as being vide a forced draft fan which may operate made of WOOd With diagonal braces 13 at the in a duct without decreasing the area which o t m t0 hold them in an upright position. may be installed so that all noise and vibra- However, it is understood that these posts tion may be eliminated. may be of any suitable material or any suit- 7 And a still further object of the invention able frame may be used. The motor 14 is is to provide a fan for a forced draft air duct mounted on the foundation and will drive which will operate in the duct without dehe Shaft 8 through a belt 15 and pulleys creasing the area to any appreciable amount 15 and 17. which is of a simple and economical construc- The cylinder 5 is provided with a pluraltion. ity of blades 18 which are made as shown in lVith these ends in view the invention em- Figure 4 and attached to the cylinder by bodies a rotary fan having curved blades, bolts or rivets, as shown. The fan is means for installing the fan in one side of an mounted in one side of the duct and pro- 35 air duct means for rotating the blades, a suiti C With a u i g which Covers the P able housing covering part of the blades with of the fan that is outside of the duct and the a seal in it and a battle plate to cooperate with housing may be divided with a joint 19 so the said fan. that a portion of it may be removed if de- Other features and advantages of the insired. One side of the housing is held in a 4o vention will appear from the following dejoint 20, which is known as a Pittsburg lock, scription taken in connection with the drawin the top of the horizontal duct and the ings, wherein: other side is held in a joint 21 in the side Figure 1 is a side vie of a bend in a duct of the vertical section of the duct. The showing the device in place. edges of the housing 2 are formed as shown 45 Figure 2 is a cross section through the duct in Figure 3 So that y will h recesses looking toward the fan. 22 and flaps 23 which may be bent down- Figure 3 is a longitudinal section through ward over the upper edge of the side mem the fan. here, which are indicated by the numeral 24.

Figure 4 is a cross section through the fan It will be observed that by bending the flaps a0 and fan housing. 23 upward the flanges. 25 at the upper edges 10( of the side members 24 may be sprung out of the recesses 22 and the housing 2 may be readily removed so that the fan may be removed through the opening in the housing. A piece of felt, as indicated by the numeral 26, may also be held in the joint 20 and positioned so that it will be engaged by the edges of two of the blades 18 at one time to form a seal as the blades leave the duct, which is very essential to the efficiency of the fan.

The duct 3 may be of any suitable shape, size or design and the fan may be positioned in it in any suitable manner. The fan may also be held in any other suitable type of frame and the frame may be attached to the duct or built integral therewith as may be desired. In the design shown the frame is attached to the sides of the duct by angle bars 27 which may be attached to the posts 11 and 12 and to the sides of the duct with a strip of deadening felt 28 between the angle bar and the duct.

In the design shown in Figure 1 a battle plate 29 is hinged in the duct at the point 30 and provided with a lever 31 which extends outward beyond the side of the duct and to which a rod or cord 32 may be attached to adjust the position of the baflle 29. It will be observed that with the battle in the position shown in full lines the area of the duct will not be decreased, and when it is r ised to the position shown in dotted lines the area will be decreased and practically all of the air passing through the duct will be forced through the fan, thereby making it possible to raise the pressure of the air considerably. It is understood that a similar baffie may be used in combination with the fan shown in Figure 6 and also that the battle may be omitted, as shown in Figure 6.

In Figure 5 the duct 3 is attached to a furnace housing which is inoicated by the numeral 33 by a clip 34 with an asbestos lining 35 for deadening the noise and eliminating the vibration.

It will be understood that changes may be made in the construction without departing from the spirit of the invention. One of which changes may be in the design of the fan, as it is understood that the central part may be made in any suitable manner and the shape of the blades may also be varied considerably and the proportionate sizes of the central part and blades may be varied as desired. It is also understood that any suitable number of blades may be used and any other suitable means may be used for rotating the fan. Other changes may be in the design or size or arrangement of the duct, and still another may be in the use of other means for varying the area of the duct.

The construction will be readily understood from the foregoing description. To use the device, the fan may be constructed and installed as shown and described and it will be observed that as the fan is rotated in a counter-clockwise direction the blades will dip the air and force ahead at a considerably greater velocity and if the battle 29 is pressure without appreciably decreasing the 7 area of the duct, which will provide a very desirable arrangement for forced air ducts of this type.

Having thus fully described the invention what I claim as new and desire to secure by Letters Patent is:

1. In a device of the class described, a plurality of blades, means for mounting the said blades on a sealed rotor, said rotor being positioned with the blades extending partially into a duct or the like, and means for covering the portion of the blades extending outside of the said duct, the means for cove"- ing the outer ends of the said blades having a seal therein and a joint whereby the seal may be readily removed, and the whole being readily removable.

2. In a device of the class described. a plurality of blades, means for mounting the said blades on a sealed rotor, said rotor being positioned with the blades extending partially into a duct or the like, leaving a free passage between the ends of the blades and side of the duct, means for covering the portion the blades extending outside of the said duet, the means for covering the outer ends of the said blades having a seal therein and a joint whereby the seal may be readily removed, and the whole being readily removable, and an adjustable battle plate for closing the opening between the ends of the blades and the opposite side of the duct.

3. In a device of the class described, a plurality of blades, means for mounting the said blades on a sealed rotor, said rotor being positioned with the blades extending partially into a duct or the like, leaving a free passage between the ends of the blades and side of the duct, means for covering the portion of the blades extending outside of? the said duct, the means for covering the outer ends of the said blades having a seal therein and a joint whereby the seal may be readily removed and the whole being readily removable, and an adjustable baffle plate for closing the opening between the ends of the blades and the opposite side of the duct, said rotor, blades and bailie plate being positioned to permit an unobstructed area corresponding to the area of the duct when the fan is not in use.

In testimony whereof I aflix my signature.

FRANK E. GRUNIVALDT.

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